Every year many people are injured or even killed by drunk drivers. Many people do not plan on drinking a large amount when they stop at a bar, but may end up doing so. Alcohol can impair the judgment of these individuals and can lead them to believe that they are sober enough to drive a car, when in reality they are under the influence and are not able to control a moving vehicle. Under these conditions the individual is not prepared for different emergencies that may occur or the individual may not see a pedestrian walking on the side of the road. The problems are further magnified if the individual drives very fast.
Thus, it would be advantageous if there were an apparatus that would prevent an individual who had been drinking from driving a car if that individual had too much to drink.